1. Field of the Invention
The present invention relates to an electrically conductive glass sheet for use as a fog-resistant glass sheet or the like.
2. Description of the Relevant Art
Electrically conductive glass sheets are employed as fog-resistant automotive window glass-sheets, for example. Certain conventional electrically conductive glass sheets include a film formed primarily of a metal oxide on a surface of the glass sheet by vacuum deposition, sputtering, or the like, as disclosed in Japanese Laid-Open Utility Model Publication Nos. 60-20449 and 60-195251, for example.
According to another known process disclosed in Japanese Patent Publication No. 33-8230, a solution containing a tin compound such as tin tetrachloride, dibutyltin oxide, dibutyltin acetate, dibutyltin chloride, or tin alkoxide, for example, is sprayed on or brought into contact with a surface of a glass sheet which is heated, or a glass sheet coated with such a solution is heated, so that the deposited tin compound is decomposed to form a film principally of a tin oxide on the glass sheet surface.
An electric current is passed through the coated film via busbars to heat the film for removing fog from the glass sheet surface.
In the case where the electrically conductive thin film is deposited on the glass sheet by sputtering or the like, the thin film has a thickness of about 0.1 micron. Since the busbars have a thickness ranging from 10 to 20 microns, the electrically conductive thin film tends to be ruptured at localized areas in junctions where it is connected to the busbars. Therefore, the electric conductivity at the junctions is liable to be reduced, thereby increasing the resistance between the busbars, with the result that the current flowing through the thin film is reduced and no sufficient heat can be produced by the thin film. Therefore, the fog resistances of the conventional electrically conductive glass sheets vary from glass sheet to glass sheet, and some of them may fail to provide a desired degree of fog resistance.
Another known anti-fog glass heat includes hot wires extending between and connected to busbars, the hot wires having wider portions connected to the busbars. However, this arrangement cannot be employed in glass sheets coated with electrically conductive thin films.